Doctors have long considered neurosyphilis – the late-stage, brain-related phase of the sexually transmitted infection – as a historical relic, the “disease of the century” in the 1800s but all but beaten down by antibiotics.

Now, though, the illness blamed for the madness of historical figures from Friedrich Nietzsche to Vladimir Lenin to Al Capone appears on the rise again in Canada and elsewhere, some experts believe.

Specialists are reporting signs of a small but significant surge in cases where syphilis triggers sometimes strange neurological effects or serious inflammatory eye disease, called uveitis.

“Uveitis from syphilis was almost unheard of 10, 20 years ago,” said Dr. Farzin Forooghian, a University of British Columbia ophthalmologist. “[Now] there is almost a little epidemic happening … Talking to my colleagues across North America at meetings, people are seeing a lot more.”

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Though opthalmologists are still trained to test for syphilis in patients with uveitis, most never really expected until recently to encounter it, said Dr. Forooghian. He has seen three cases just in the last year, however. One female patient was offended that he even suggested a syphilis test – saying she had only ever had one sexual partner – but ended up testing positive. “It can be awkward,” the physician said.

One recent journal article advises neurologists to consider syphilis when they diagnose patients whose problems point to Parkinson’s disease or some other “movement disorder.”

‘Syphilis has probably had quite a major impact on the history of mankind, in terms of the way it’s affected human behaviour’

If diagnosed soon enough and treated with a two-week course of intravenous penicillin, neurosyphilis can be cured and the brain-related symptoms usually eliminated, doctors say. If allowed to progress too long, though, permanent neurological damage including blindness and death is a possibility.

“[Brain doctors] are going to see these patients,” said Dr. Anthony Lang, a University of Toronto neurology professor who specializes in movement disorders. “And I think if we’re vigilant and aware that this disease is once again on the rise – and it can present in a variety of ways – we’ll be able to pick it up earlier.”

Dr. Lang became interested in the issue after seeing a patient with a strange mix of symptoms.

Some hinted at a movement disorder – including jerky movements, lack of co-ordination, numbness in one leg and impaired speech – but the 44-year-old had also reported bouts of depression and had quit his job, upset that some of his colleagues were questioning his mental competence.

His condition deteriorated rapidly, with abnormal drowsiness and amnesia, until finally he was admitted to an emergency department – and diagnosed with syphilis, said Dr. Lang’s paper in the journal Movement Disorders. Most of the symptoms disappeared after treatment.

Neurosyphilis affects a significant chunk of patients whose illness goes untreated, but often does not appear until several years after infection, said Dr. Lynora Saxinger, a communicable-disease expert at the University of Alberta. As the bacteria spreads more widely, a bigger wave of syphilis-caused problems like mood disorders and stroke in young people may be coming, she said.

Not all experts are convinced an upsurge in classic neurospyhilis is taking shape, however. Dr. Vanessa Allen, a medical microbiologist at the University of Toronto who supervises syphilis testing in Ontario, said most brain effects of the bacteria being seen now are likely less-serious ones that come earlier in the disease’s progression.

‘I think if we’re vigilant and aware that this disease is once again on the rise – and it can present in a variety of ways – we’ll be able to pick it up earlier’

Syphilis generally had begun to die off in the Western world toward the end of the 1900s, before a sudden resurgence in the last decade or so.

The number and per-capita rate of cases soared more than 10-fold between 1997 and 2009, with almost 1,700 infections a year reported recently, according to the Public Health Agency of Canada. One theory is that wider practice of oral sex – a prime route of syphilis transmission – is to blame, said Dr. Allen.

The disease typically progresses from an acute phase that might include chancres and swollen lymph glands, to a secondary stage with rash, fever, malaise, headaches and sometimes meningitis and eye disease. A symptom-free latent period can follow for a year, or much longer, sometimes leading to the third phase, where neurosyphilis and heart problems may occur.

“Syphilis has probably had quite a major impact on the history of mankind, in terms of the way it’s affected human behaviour,” said Dr. Lang.

That changed in the antibiotic era, as the drugs halted most cases before they advanced to the most serious, third level, until recently at least.